The fast method
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18% of 50 = 50% of 18 = 9
How it works
Choose the direction that is easier to calculate.
Why it works
x/100 × y = y/100 × x.
Use it when
Works for any real percentage and value.
Watch out for
Choose the form that is actually simpler.
Verified examples
Example 1
Find 18% of 50
Swap to 50% of 18
9Example 2
Find 4% of 75
Swap to 75% of 4
3Example 3
Find 25% of 16
Swap to 16% of 25
4